2.2.tex

\documentclass[a4paper,12pt]{article}
\usepackage{listings}
\lstset{language=Lisp}

\begin{document}
\begin{lstlisting}
(define (make-segment start end) (cons start end))
(define (start-segment s) (car s))
(define (end-segment s) (cdr s))
(define (make-point x y) (cons x y))
(define (x-point p) (car p))
(define (y-point p) (cdr p))
(define (midpoint-segment s)
  (make-point (/ (+ (x-point (end-segment s))
                    (x-point (start-segment s)))
                 2)
              (/ (+ (y-point (end-segment s))
                    (y-point (start-segment s)))
                 2)))
(define (print-point p)
  (display "(")
  (display (x-point p))
  (display ",")
  (display (y-point p))
  (display ")")
  (newline))
\end{lstlisting}
\end{document}